The invention relates to an apparatus for passing a substantially flat workpiece into and out of an evacuated coating chamber through airlocks and for moving the workpiece into and out of the range of a coating source for the purpose of treating the workpiece surface.
An apparatus of the kind in question is known (U.S. Pat. No. 3,874,525) which has a coating chamber in which a two-armed gripping tool is journaled on a vertical axis. This two-armed tool has at its diametrically opposite ends forks which can be moved toward and away from one another in a vertical plane by means of a rack-and-pinion drive with a drive motor. Also, two brackets are provided in the coating chamber, one of which is disposed underneath an airlock in the cover of the coating chamber and the other under an electron gun on the side opposite the first bracket.
This known apparatus has the disadvantage that the two-armed gripping tool is of comparatively complex construction and also is not very reliable in operation since the complex rack-and-pinion drive produces momentum. Also, in this apparatus the danger exists that the workpiece will not be perfectly grasped by the fork-like tool and then will be picked up in a canted position or else will completely escape from the tool and drop on the floor of the coating chamber, resulting in a blockage or in the failure of the entire apparatus. Lastly, the known apparatus requires a great amount of head space, which creates the need for an undesirably bulky coating chamber.
The invention is therefore addressed to the task of creating an apparatus which will distinguish itself from known apparatus by greater reliability. Its coating chamber is to have an especially small volume, and it is to be suitable even for particularly delicate, thin-walled workpieces made of flexible material--so-called substrates or wafers.